libstdc++
fstream.tcc
1 // File based streams -*- C++ -*-
2 
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
4 // 2007, 2008, 2009
5 // Free Software Foundation, Inc.
6 //
7 // This file is part of the GNU ISO C++ Library. This library is free
8 // software; you can redistribute it and/or modify it under the
9 // terms of the GNU General Public License as published by the
10 // Free Software Foundation; either version 3, or (at your option)
11 // any later version.
12 
13 // This library is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
17 
18 // Under Section 7 of GPL version 3, you are granted additional
19 // permissions described in the GCC Runtime Library Exception, version
20 // 3.1, as published by the Free Software Foundation.
21 
22 // You should have received a copy of the GNU General Public License and
23 // a copy of the GCC Runtime Library Exception along with this program;
24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25 // <http://www.gnu.org/licenses/>.
26 
27 /** @file fstream.tcc
28  * This is an internal header file, included by other library headers.
29  * You should not attempt to use it directly.
30  */
31 
32 //
33 // ISO C++ 14882: 27.8 File-based streams
34 //
35 
36 #ifndef _FSTREAM_TCC
37 #define _FSTREAM_TCC 1
38 
39 #pragma GCC system_header
40 
41 #include <cxxabi-forced.h>
42 
43 _GLIBCXX_BEGIN_NAMESPACE(std)
44 
45  template<typename _CharT, typename _Traits>
46  void
47  basic_filebuf<_CharT, _Traits>::
48  _M_allocate_internal_buffer()
49  {
50  // Allocate internal buffer only if one doesn't already exist
51  // (either allocated or provided by the user via setbuf).
52  if (!_M_buf_allocated && !_M_buf)
53  {
54  _M_buf = new char_type[_M_buf_size];
55  _M_buf_allocated = true;
56  }
57  }
58 
59  template<typename _CharT, typename _Traits>
60  void
61  basic_filebuf<_CharT, _Traits>::
62  _M_destroy_internal_buffer() throw()
63  {
64  if (_M_buf_allocated)
65  {
66  delete [] _M_buf;
67  _M_buf = NULL;
68  _M_buf_allocated = false;
69  }
70  delete [] _M_ext_buf;
71  _M_ext_buf = NULL;
72  _M_ext_buf_size = 0;
73  _M_ext_next = NULL;
74  _M_ext_end = NULL;
75  }
76 
77  template<typename _CharT, typename _Traits>
78  basic_filebuf<_CharT, _Traits>::
79  basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock),
80  _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
81  _M_state_last(), _M_buf(NULL), _M_buf_size(BUFSIZ),
82  _M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(),
83  _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
84  _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
85  _M_ext_end(0)
86  {
87  if (has_facet<__codecvt_type>(this->_M_buf_locale))
88  _M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
89  }
90 
91  template<typename _CharT, typename _Traits>
92  typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
93  basic_filebuf<_CharT, _Traits>::
94  open(const char* __s, ios_base::openmode __mode)
95  {
96  __filebuf_type *__ret = NULL;
97  if (!this->is_open())
98  {
99  _M_file.open(__s, __mode);
100  if (this->is_open())
101  {
102  _M_allocate_internal_buffer();
103  _M_mode = __mode;
104 
105  // Setup initial buffer to 'uncommitted' mode.
106  _M_reading = false;
107  _M_writing = false;
108  _M_set_buffer(-1);
109 
110  // Reset to initial state.
111  _M_state_last = _M_state_cur = _M_state_beg;
112 
113  // 27.8.1.3,4
114  if ((__mode & ios_base::ate)
115  && this->seekoff(0, ios_base::end, __mode)
116  == pos_type(off_type(-1)))
117  this->close();
118  else
119  __ret = this;
120  }
121  }
122  return __ret;
123  }
124 
125  template<typename _CharT, typename _Traits>
126  typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
127  basic_filebuf<_CharT, _Traits>::
128  close()
129  {
130  if (!this->is_open())
131  return NULL;
132 
133  bool __testfail = false;
134  {
135  // NB: Do this here so that re-opened filebufs will be cool...
136  struct __close_sentry
137  {
138  basic_filebuf *__fb;
139  __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { }
140  ~__close_sentry ()
141  {
142  __fb->_M_mode = ios_base::openmode(0);
143  __fb->_M_pback_init = false;
144  __fb->_M_destroy_internal_buffer();
145  __fb->_M_reading = false;
146  __fb->_M_writing = false;
147  __fb->_M_set_buffer(-1);
148  __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg;
149  }
150  } __cs (this);
151 
152  __try
153  {
154  if (!_M_terminate_output())
155  __testfail = true;
156  }
157  __catch(__cxxabiv1::__forced_unwind&)
158  {
159  _M_file.close();
160  __throw_exception_again;
161  }
162  __catch(...)
163  { __testfail = true; }
164  }
165 
166  if (!_M_file.close())
167  __testfail = true;
168 
169  if (__testfail)
170  return NULL;
171  else
172  return this;
173  }
174 
175  template<typename _CharT, typename _Traits>
176  streamsize
177  basic_filebuf<_CharT, _Traits>::
178  showmanyc()
179  {
180  streamsize __ret = -1;
181  const bool __testin = _M_mode & ios_base::in;
182  if (__testin && this->is_open())
183  {
184  // For a stateful encoding (-1) the pending sequence might be just
185  // shift and unshift prefixes with no actual character.
186  __ret = this->egptr() - this->gptr();
187 
188 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
189  // About this workaround, see libstdc++/20806.
190  const bool __testbinary = _M_mode & ios_base::binary;
191  if (__check_facet(_M_codecvt).encoding() >= 0
192  && __testbinary)
193 #else
194  if (__check_facet(_M_codecvt).encoding() >= 0)
195 #endif
196  __ret += _M_file.showmanyc() / _M_codecvt->max_length();
197  }
198  return __ret;
199  }
200 
201  template<typename _CharT, typename _Traits>
202  typename basic_filebuf<_CharT, _Traits>::int_type
203  basic_filebuf<_CharT, _Traits>::
204  underflow()
205  {
206  int_type __ret = traits_type::eof();
207  const bool __testin = _M_mode & ios_base::in;
208  if (__testin && !_M_writing)
209  {
210  // Check for pback madness, and if so switch back to the
211  // normal buffers and jet outta here before expensive
212  // fileops happen...
213  _M_destroy_pback();
214 
215  if (this->gptr() < this->egptr())
216  return traits_type::to_int_type(*this->gptr());
217 
218  // Get and convert input sequence.
219  const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
220 
221  // Will be set to true if ::read() returns 0 indicating EOF.
222  bool __got_eof = false;
223  // Number of internal characters produced.
224  streamsize __ilen = 0;
225  codecvt_base::result __r = codecvt_base::ok;
226  if (__check_facet(_M_codecvt).always_noconv())
227  {
228  __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
229  __buflen);
230  if (__ilen == 0)
231  __got_eof = true;
232  }
233  else
234  {
235  // Worst-case number of external bytes.
236  // XXX Not done encoding() == -1.
237  const int __enc = _M_codecvt->encoding();
238  streamsize __blen; // Minimum buffer size.
239  streamsize __rlen; // Number of chars to read.
240  if (__enc > 0)
241  __blen = __rlen = __buflen * __enc;
242  else
243  {
244  __blen = __buflen + _M_codecvt->max_length() - 1;
245  __rlen = __buflen;
246  }
247  const streamsize __remainder = _M_ext_end - _M_ext_next;
248  __rlen = __rlen > __remainder ? __rlen - __remainder : 0;
249 
250  // An imbue in 'read' mode implies first converting the external
251  // chars already present.
252  if (_M_reading && this->egptr() == this->eback() && __remainder)
253  __rlen = 0;
254 
255  // Allocate buffer if necessary and move unconverted
256  // bytes to front.
257  if (_M_ext_buf_size < __blen)
258  {
259  char* __buf = new char[__blen];
260  if (__remainder)
261  __builtin_memcpy(__buf, _M_ext_next, __remainder);
262 
263  delete [] _M_ext_buf;
264  _M_ext_buf = __buf;
265  _M_ext_buf_size = __blen;
266  }
267  else if (__remainder)
268  __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
269 
270  _M_ext_next = _M_ext_buf;
271  _M_ext_end = _M_ext_buf + __remainder;
272  _M_state_last = _M_state_cur;
273 
274  do
275  {
276  if (__rlen > 0)
277  {
278  // Sanity check!
279  // This may fail if the return value of
280  // codecvt::max_length() is bogus.
281  if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
282  {
283  __throw_ios_failure(__N("basic_filebuf::underflow "
284  "codecvt::max_length() "
285  "is not valid"));
286  }
287  streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
288  if (__elen == 0)
289  __got_eof = true;
290  else if (__elen == -1)
291  break;
292  _M_ext_end += __elen;
293  }
294 
295  char_type* __iend = this->eback();
296  if (_M_ext_next < _M_ext_end)
297  __r = _M_codecvt->in(_M_state_cur, _M_ext_next,
298  _M_ext_end, _M_ext_next,
299  this->eback(),
300  this->eback() + __buflen, __iend);
301  if (__r == codecvt_base::noconv)
302  {
303  size_t __avail = _M_ext_end - _M_ext_buf;
304  __ilen = std::min(__avail, __buflen);
305  traits_type::copy(this->eback(),
306  reinterpret_cast<char_type*>
307  (_M_ext_buf), __ilen);
308  _M_ext_next = _M_ext_buf + __ilen;
309  }
310  else
311  __ilen = __iend - this->eback();
312 
313  // _M_codecvt->in may return error while __ilen > 0: this is
314  // ok, and actually occurs in case of mixed encodings (e.g.,
315  // XML files).
316  if (__r == codecvt_base::error)
317  break;
318 
319  __rlen = 1;
320  }
321  while (__ilen == 0 && !__got_eof);
322  }
323 
324  if (__ilen > 0)
325  {
326  _M_set_buffer(__ilen);
327  _M_reading = true;
328  __ret = traits_type::to_int_type(*this->gptr());
329  }
330  else if (__got_eof)
331  {
332  // If the actual end of file is reached, set 'uncommitted'
333  // mode, thus allowing an immediate write without an
334  // intervening seek.
335  _M_set_buffer(-1);
336  _M_reading = false;
337  // However, reaching it while looping on partial means that
338  // the file has got an incomplete character.
339  if (__r == codecvt_base::partial)
340  __throw_ios_failure(__N("basic_filebuf::underflow "
341  "incomplete character in file"));
342  }
343  else if (__r == codecvt_base::error)
344  __throw_ios_failure(__N("basic_filebuf::underflow "
345  "invalid byte sequence in file"));
346  else
347  __throw_ios_failure(__N("basic_filebuf::underflow "
348  "error reading the file"));
349  }
350  return __ret;
351  }
352 
353  template<typename _CharT, typename _Traits>
354  typename basic_filebuf<_CharT, _Traits>::int_type
355  basic_filebuf<_CharT, _Traits>::
356  pbackfail(int_type __i)
357  {
358  int_type __ret = traits_type::eof();
359  const bool __testin = _M_mode & ios_base::in;
360  if (__testin && !_M_writing)
361  {
362  // Remember whether the pback buffer is active, otherwise below
363  // we may try to store in it a second char (libstdc++/9761).
364  const bool __testpb = _M_pback_init;
365  const bool __testeof = traits_type::eq_int_type(__i, __ret);
366  int_type __tmp;
367  if (this->eback() < this->gptr())
368  {
369  this->gbump(-1);
370  __tmp = traits_type::to_int_type(*this->gptr());
371  }
372  else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
373  {
374  __tmp = this->underflow();
375  if (traits_type::eq_int_type(__tmp, __ret))
376  return __ret;
377  }
378  else
379  {
380  // At the beginning of the buffer, need to make a
381  // putback position available. But the seek may fail
382  // (f.i., at the beginning of a file, see
383  // libstdc++/9439) and in that case we return
384  // traits_type::eof().
385  return __ret;
386  }
387 
388  // Try to put back __i into input sequence in one of three ways.
389  // Order these tests done in is unspecified by the standard.
390  if (!__testeof && traits_type::eq_int_type(__i, __tmp))
391  __ret = __i;
392  else if (__testeof)
393  __ret = traits_type::not_eof(__i);
394  else if (!__testpb)
395  {
396  _M_create_pback();
397  _M_reading = true;
398  *this->gptr() = traits_type::to_char_type(__i);
399  __ret = __i;
400  }
401  }
402  return __ret;
403  }
404 
405  template<typename _CharT, typename _Traits>
406  typename basic_filebuf<_CharT, _Traits>::int_type
407  basic_filebuf<_CharT, _Traits>::
408  overflow(int_type __c)
409  {
410  int_type __ret = traits_type::eof();
411  const bool __testeof = traits_type::eq_int_type(__c, __ret);
412  const bool __testout = _M_mode & ios_base::out;
413  if (__testout && !_M_reading)
414  {
415  if (this->pbase() < this->pptr())
416  {
417  // If appropriate, append the overflow char.
418  if (!__testeof)
419  {
420  *this->pptr() = traits_type::to_char_type(__c);
421  this->pbump(1);
422  }
423 
424  // Convert pending sequence to external representation,
425  // and output.
426  if (_M_convert_to_external(this->pbase(),
427  this->pptr() - this->pbase()))
428  {
429  _M_set_buffer(0);
430  __ret = traits_type::not_eof(__c);
431  }
432  }
433  else if (_M_buf_size > 1)
434  {
435  // Overflow in 'uncommitted' mode: set _M_writing, set
436  // the buffer to the initial 'write' mode, and put __c
437  // into the buffer.
438  _M_set_buffer(0);
439  _M_writing = true;
440  if (!__testeof)
441  {
442  *this->pptr() = traits_type::to_char_type(__c);
443  this->pbump(1);
444  }
445  __ret = traits_type::not_eof(__c);
446  }
447  else
448  {
449  // Unbuffered.
450  char_type __conv = traits_type::to_char_type(__c);
451  if (__testeof || _M_convert_to_external(&__conv, 1))
452  {
453  _M_writing = true;
454  __ret = traits_type::not_eof(__c);
455  }
456  }
457  }
458  return __ret;
459  }
460 
461  template<typename _CharT, typename _Traits>
462  bool
463  basic_filebuf<_CharT, _Traits>::
464  _M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
465  {
466  // Sizes of external and pending output.
467  streamsize __elen;
468  streamsize __plen;
469  if (__check_facet(_M_codecvt).always_noconv())
470  {
471  __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
472  __plen = __ilen;
473  }
474  else
475  {
476  // Worst-case number of external bytes needed.
477  // XXX Not done encoding() == -1.
478  streamsize __blen = __ilen * _M_codecvt->max_length();
479  char* __buf = static_cast<char*>(__builtin_alloca(__blen));
480 
481  char* __bend;
482  const char_type* __iend;
483  codecvt_base::result __r;
484  __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
485  __iend, __buf, __buf + __blen, __bend);
486 
487  if (__r == codecvt_base::ok || __r == codecvt_base::partial)
488  __blen = __bend - __buf;
489  else if (__r == codecvt_base::noconv)
490  {
491  // Same as the always_noconv case above.
492  __buf = reinterpret_cast<char*>(__ibuf);
493  __blen = __ilen;
494  }
495  else
496  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
497  "conversion error"));
498 
499  __elen = _M_file.xsputn(__buf, __blen);
500  __plen = __blen;
501 
502  // Try once more for partial conversions.
503  if (__r == codecvt_base::partial && __elen == __plen)
504  {
505  const char_type* __iresume = __iend;
506  streamsize __rlen = this->pptr() - __iend;
507  __r = _M_codecvt->out(_M_state_cur, __iresume,
508  __iresume + __rlen, __iend, __buf,
509  __buf + __blen, __bend);
510  if (__r != codecvt_base::error)
511  {
512  __rlen = __bend - __buf;
513  __elen = _M_file.xsputn(__buf, __rlen);
514  __plen = __rlen;
515  }
516  else
517  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
518  "conversion error"));
519  }
520  }
521  return __elen == __plen;
522  }
523 
524  template<typename _CharT, typename _Traits>
525  streamsize
526  basic_filebuf<_CharT, _Traits>::
527  xsgetn(_CharT* __s, streamsize __n)
528  {
529  // Clear out pback buffer before going on to the real deal...
530  streamsize __ret = 0;
531  if (_M_pback_init)
532  {
533  if (__n > 0 && this->gptr() == this->eback())
534  {
535  *__s++ = *this->gptr();
536  this->gbump(1);
537  __ret = 1;
538  --__n;
539  }
540  _M_destroy_pback();
541  }
542 
543  // Optimization in the always_noconv() case, to be generalized in the
544  // future: when __n > __buflen we read directly instead of using the
545  // buffer repeatedly.
546  const bool __testin = _M_mode & ios_base::in;
547  const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
548 
549  if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
550  && __testin && !_M_writing)
551  {
552  // First, copy the chars already present in the buffer.
553  const streamsize __avail = this->egptr() - this->gptr();
554  if (__avail != 0)
555  {
556  if (__avail == 1)
557  *__s = *this->gptr();
558  else
559  traits_type::copy(__s, this->gptr(), __avail);
560  __s += __avail;
561  this->gbump(__avail);
562  __ret += __avail;
563  __n -= __avail;
564  }
565 
566  // Need to loop in case of short reads (relatively common
567  // with pipes).
568  streamsize __len;
569  for (;;)
570  {
571  __len = _M_file.xsgetn(reinterpret_cast<char*>(__s),
572  __n);
573  if (__len == -1)
574  __throw_ios_failure(__N("basic_filebuf::xsgetn "
575  "error reading the file"));
576  if (__len == 0)
577  break;
578 
579  __n -= __len;
580  __ret += __len;
581  if (__n == 0)
582  break;
583 
584  __s += __len;
585  }
586 
587  if (__n == 0)
588  {
589  _M_set_buffer(0);
590  _M_reading = true;
591  }
592  else if (__len == 0)
593  {
594  // If end of file is reached, set 'uncommitted'
595  // mode, thus allowing an immediate write without
596  // an intervening seek.
597  _M_set_buffer(-1);
598  _M_reading = false;
599  }
600  }
601  else
602  __ret += __streambuf_type::xsgetn(__s, __n);
603 
604  return __ret;
605  }
606 
607  template<typename _CharT, typename _Traits>
608  streamsize
609  basic_filebuf<_CharT, _Traits>::
610  xsputn(const _CharT* __s, streamsize __n)
611  {
612  // Optimization in the always_noconv() case, to be generalized in the
613  // future: when __n is sufficiently large we write directly instead of
614  // using the buffer.
615  streamsize __ret = 0;
616  const bool __testout = _M_mode & ios_base::out;
617  if (__check_facet(_M_codecvt).always_noconv()
618  && __testout && !_M_reading)
619  {
620  // Measurement would reveal the best choice.
621  const streamsize __chunk = 1ul << 10;
622  streamsize __bufavail = this->epptr() - this->pptr();
623 
624  // Don't mistake 'uncommitted' mode buffered with unbuffered.
625  if (!_M_writing && _M_buf_size > 1)
626  __bufavail = _M_buf_size - 1;
627 
628  const streamsize __limit = std::min(__chunk, __bufavail);
629  if (__n >= __limit)
630  {
631  const streamsize __buffill = this->pptr() - this->pbase();
632  const char* __buf = reinterpret_cast<const char*>(this->pbase());
633  __ret = _M_file.xsputn_2(__buf, __buffill,
634  reinterpret_cast<const char*>(__s),
635  __n);
636  if (__ret == __buffill + __n)
637  {
638  _M_set_buffer(0);
639  _M_writing = true;
640  }
641  if (__ret > __buffill)
642  __ret -= __buffill;
643  else
644  __ret = 0;
645  }
646  else
647  __ret = __streambuf_type::xsputn(__s, __n);
648  }
649  else
650  __ret = __streambuf_type::xsputn(__s, __n);
651  return __ret;
652  }
653 
654  template<typename _CharT, typename _Traits>
655  typename basic_filebuf<_CharT, _Traits>::__streambuf_type*
656  basic_filebuf<_CharT, _Traits>::
657  setbuf(char_type* __s, streamsize __n)
658  {
659  if (!this->is_open())
660  {
661  if (__s == 0 && __n == 0)
662  _M_buf_size = 1;
663  else if (__s && __n > 0)
664  {
665  // This is implementation-defined behavior, and assumes that
666  // an external char_type array of length __n exists and has
667  // been pre-allocated. If this is not the case, things will
668  // quickly blow up. When __n > 1, __n - 1 positions will be
669  // used for the get area, __n - 1 for the put area and 1
670  // position to host the overflow char of a full put area.
671  // When __n == 1, 1 position will be used for the get area
672  // and 0 for the put area, as in the unbuffered case above.
673  _M_buf = __s;
674  _M_buf_size = __n;
675  }
676  }
677  return this;
678  }
679 
680 
681  // According to 27.8.1.4 p11 - 13, seekoff should ignore the last
682  // argument (of type openmode).
683  template<typename _CharT, typename _Traits>
684  typename basic_filebuf<_CharT, _Traits>::pos_type
685  basic_filebuf<_CharT, _Traits>::
686  seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
687  {
688  int __width = 0;
689  if (_M_codecvt)
690  __width = _M_codecvt->encoding();
691  if (__width < 0)
692  __width = 0;
693 
694  pos_type __ret = pos_type(off_type(-1));
695  const bool __testfail = __off != 0 && __width <= 0;
696  if (this->is_open() && !__testfail)
697  {
698  // Ditch any pback buffers to avoid confusion.
699  _M_destroy_pback();
700 
701  // Correct state at destination. Note that this is the correct
702  // state for the current position during output, because
703  // codecvt::unshift() returns the state to the initial state.
704  // This is also the correct state at the end of the file because
705  // an unshift sequence should have been written at the end.
706  __state_type __state = _M_state_beg;
707  off_type __computed_off = __off * __width;
708  if (_M_reading && __way == ios_base::cur)
709  {
710  if (_M_codecvt->always_noconv())
711  __computed_off += this->gptr() - this->egptr();
712  else
713  {
714  // Calculate offset from _M_ext_buf that corresponds
715  // to gptr(). Note: uses _M_state_last, which
716  // corresponds to eback().
717  const int __gptr_off =
718  _M_codecvt->length(_M_state_last, _M_ext_buf, _M_ext_next,
719  this->gptr() - this->eback());
720  __computed_off += _M_ext_buf + __gptr_off - _M_ext_end;
721 
722  // _M_state_last is modified by codecvt::length() so
723  // it now corresponds to gptr().
724  __state = _M_state_last;
725  }
726  }
727  __ret = _M_seek(__computed_off, __way, __state);
728  }
729  return __ret;
730  }
731 
732  // _GLIBCXX_RESOLVE_LIB_DEFECTS
733  // 171. Strange seekpos() semantics due to joint position
734  // According to the resolution of DR 171, seekpos should ignore the last
735  // argument (of type openmode).
736  template<typename _CharT, typename _Traits>
737  typename basic_filebuf<_CharT, _Traits>::pos_type
738  basic_filebuf<_CharT, _Traits>::
739  seekpos(pos_type __pos, ios_base::openmode)
740  {
741  pos_type __ret = pos_type(off_type(-1));
742  if (this->is_open())
743  {
744  // Ditch any pback buffers to avoid confusion.
745  _M_destroy_pback();
746  __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
747  }
748  return __ret;
749  }
750 
751  template<typename _CharT, typename _Traits>
752  typename basic_filebuf<_CharT, _Traits>::pos_type
753  basic_filebuf<_CharT, _Traits>::
754  _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
755  {
756  pos_type __ret = pos_type(off_type(-1));
757  if (_M_terminate_output())
758  {
759  // Returns pos_type(off_type(-1)) in case of failure.
760  __ret = pos_type(_M_file.seekoff(__off, __way));
761  if (__ret != pos_type(off_type(-1)))
762  {
763  _M_reading = false;
764  _M_writing = false;
765  _M_ext_next = _M_ext_end = _M_ext_buf;
766  _M_set_buffer(-1);
767  _M_state_cur = __state;
768  __ret.state(_M_state_cur);
769  }
770  }
771  return __ret;
772  }
773 
774  template<typename _CharT, typename _Traits>
775  bool
776  basic_filebuf<_CharT, _Traits>::
777  _M_terminate_output()
778  {
779  // Part one: update the output sequence.
780  bool __testvalid = true;
781  if (this->pbase() < this->pptr())
782  {
783  const int_type __tmp = this->overflow();
784  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
785  __testvalid = false;
786  }
787 
788  // Part two: output unshift sequence.
789  if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
790  && __testvalid)
791  {
792  // Note: this value is arbitrary, since there is no way to
793  // get the length of the unshift sequence from codecvt,
794  // without calling unshift.
795  const size_t __blen = 128;
796  char __buf[__blen];
797  codecvt_base::result __r;
798  streamsize __ilen = 0;
799 
800  do
801  {
802  char* __next;
803  __r = _M_codecvt->unshift(_M_state_cur, __buf,
804  __buf + __blen, __next);
805  if (__r == codecvt_base::error)
806  __testvalid = false;
807  else if (__r == codecvt_base::ok ||
808  __r == codecvt_base::partial)
809  {
810  __ilen = __next - __buf;
811  if (__ilen > 0)
812  {
813  const streamsize __elen = _M_file.xsputn(__buf, __ilen);
814  if (__elen != __ilen)
815  __testvalid = false;
816  }
817  }
818  }
819  while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
820 
821  if (__testvalid)
822  {
823  // This second call to overflow() is required by the standard,
824  // but it's not clear why it's needed, since the output buffer
825  // should be empty by this point (it should have been emptied
826  // in the first call to overflow()).
827  const int_type __tmp = this->overflow();
828  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
829  __testvalid = false;
830  }
831  }
832  return __testvalid;
833  }
834 
835  template<typename _CharT, typename _Traits>
836  int
837  basic_filebuf<_CharT, _Traits>::
838  sync()
839  {
840  // Make sure that the internal buffer resyncs its idea of
841  // the file position with the external file.
842  int __ret = 0;
843  if (this->pbase() < this->pptr())
844  {
845  const int_type __tmp = this->overflow();
846  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
847  __ret = -1;
848  }
849  return __ret;
850  }
851 
852  template<typename _CharT, typename _Traits>
853  void
854  basic_filebuf<_CharT, _Traits>::
855  imbue(const locale& __loc)
856  {
857  bool __testvalid = true;
858 
859  const __codecvt_type* _M_codecvt_tmp = 0;
860  if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
861  _M_codecvt_tmp = &use_facet<__codecvt_type>(__loc);
862 
863  if (this->is_open())
864  {
865  // encoding() == -1 is ok only at the beginning.
866  if ((_M_reading || _M_writing)
867  && __check_facet(_M_codecvt).encoding() == -1)
868  __testvalid = false;
869  else
870  {
871  if (_M_reading)
872  {
873  if (__check_facet(_M_codecvt).always_noconv())
874  {
875  if (_M_codecvt_tmp
876  && !__check_facet(_M_codecvt_tmp).always_noconv())
877  __testvalid = this->seekoff(0, ios_base::cur, _M_mode)
878  != pos_type(off_type(-1));
879  }
880  else
881  {
882  // External position corresponding to gptr().
883  _M_ext_next = _M_ext_buf
884  + _M_codecvt->length(_M_state_last, _M_ext_buf, _M_ext_next,
885  this->gptr() - this->eback());
886  const streamsize __remainder = _M_ext_end - _M_ext_next;
887  if (__remainder)
888  __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
889 
890  _M_ext_next = _M_ext_buf;
891  _M_ext_end = _M_ext_buf + __remainder;
892  _M_set_buffer(-1);
893  _M_state_last = _M_state_cur = _M_state_beg;
894  }
895  }
896  else if (_M_writing && (__testvalid = _M_terminate_output()))
897  _M_set_buffer(-1);
898  }
899  }
900 
901  if (__testvalid)
902  _M_codecvt = _M_codecvt_tmp;
903  else
904  _M_codecvt = 0;
905  }
906 
907  // Inhibit implicit instantiations for required instantiations,
908  // which are defined via explicit instantiations elsewhere.
909  // NB: This syntax is a GNU extension.
910 #if _GLIBCXX_EXTERN_TEMPLATE
911  extern template class basic_filebuf<char>;
912  extern template class basic_ifstream<char>;
913  extern template class basic_ofstream<char>;
914  extern template class basic_fstream<char>;
915 
916 #ifdef _GLIBCXX_USE_WCHAR_T
917  extern template class basic_filebuf<wchar_t>;
918  extern template class basic_ifstream<wchar_t>;
919  extern template class basic_ofstream<wchar_t>;
920  extern template class basic_fstream<wchar_t>;
921 #endif
922 #endif
923 
924 _GLIBCXX_END_NAMESPACE
925 
926 #endif